Cost effective rendering for 3D displays

ABSTRACT

A method and apparatus for rendering image data on a 3D display is disclosed. A first image signal is received and then at least one colour component of the first image signal is rendered in reduced spatial resolution to produce a second image signal. The second image signal is spatial filtered wherein spatial errors and view errors are balanced when reconstructing a full resolution signal for the display.

This invention pertains in general to the field of image signalprocessing. More particularly the invention relates to processing ofimage signals for display on 3D lenticular or barrier displays, and moreparticularly to preserving the perceived image quality of a signal whenrendering image signals for display on 3D lenticular or barrierdisplays.

3D imagery is a function of binocular parallax, which provides relativedepth perception to the viewer. As an image of a fixated object falls ondisparate retinal points, the resulting retinal disparity providesstimulus from which the sense of stereopsis is created by the viewer'svisual system. Within the visual system separate neurologicalsub-systems specializing in different aspects of stereopsis such as fineor coarse stereopsis, or motion-in-depth, static or lateral motionstereopsis performing in combination or separately based upon thestimulus, create a 3D image for the viewer. Various means whereby 2Dimages may be presented to the viewer's visual system as 3D images arecurrently in existence.

In WO/99/05559 a method for controlling pixel addressing of a displaydevice to drive the display device as an multi-view auto-stereoscopicdisplay when a lenticular screen is overlaid and image data for multipleviews to be interlaced is provided. Based on data defining at least thelenticular screen lenticule pitch, and the global lenticular screenposition relative to the display device, for each display colour pixel,a derivation is made as to which of the N views it is to carry. Thecorresponding pixel data for the assigned view is then selected as thedisplay pixel data. Although the image quality of the multi-view displaydevice controlled on basis of the method as described in WO 99/05559 isrelatively good, the amount of signal processing needed to produce thedisplayed image is quite large.

Current 3D graphic systems utilizing 2D raster displays typicallyachieve realistic 3D effects by rendering objects on the 2D graphicsraster display using perspective algorithms.

FIG. 1 illustrates a known signal processing system for rendering 2.5Dvideo signals on 3D displays, wherein the display is constructed suchthat a view is mapped on individual sub-pixels. The rendering system 100receives a YUVD signal which is converted into a RGBD signal in a knownmanner by a converter 102. The RGBD is then scaled by a scaler 104 intothe individual R, G, B, D components. A view renderer(s) 106 thenrenders the RD, GD, and BD signals to produce new R, G, B signals. Theview renderer 106 is instantiated 9 times. Each instantiation operateson a single colour component. The R, G, B signals are then merged backtogether in a merge unit 108 to produce a final RGB signal which canthen be displayed on a display screen 110.

FIG. 2 illustrates the view numbers on the respective sub-pixels for a9-view display according to the signal processing system illustrated inFIG. 1. It performs two main functions: the depth transformation andresampling to generate the proper sub-pixel grid. The computationalcomplexity of a view renderer is significant in view of currenttechnology as it operates on sub-pixel positions of high displayresolutions. Further, the computational load for each of the colourcomponents is equal. Thus, there is a tremendous amount of computingthat must be performed to render the 2.5D video signal on the 3Ddisplay. This computational load requires a significant amount ofprocessing power and energy, since it is performed in real-time.

Hence, an improved signal processing system would be advantageous and inparticular a rendering system which significantly reduces the amount ofcomputations needed to render the image data on a 3D display whilebalancing spatial errors and view errors to produce a signal withacceptable image quality.

Accordingly, the present invention preferably seeks to mitigate,alleviate or eliminate one or more of the above-identified deficienciesin the art and disadvantages singly or in any combination and solves atleast the above mentioned problems, at least partly, by providing amethod, an apparatus, and a computer-readable medium that provides anefficient rendering of image data on a 3D display, according to theappended patent claims.

The invention aims at significant cost savings while preserving theperceived image quality when rendering image data on a 3D lenticular orbarrier display. This is mainly performed by processing in the YUVdomain and reduction of the U/V resolution. The view and spatial errorsare balanced by novel selection of sub-pixel values in the YUV/RGBmatrix. The perceived image quality is only marginally reduced.Furthermore, the processing in the YUV domain enables adaptiveprocessing of depth dependent brightness/contrast to fit seamlessly inthe processing chain. This improves the perceived depth impression. Thisinformation reduces the computational load by at least 50%.

According to aspects of the invention, a method, an apparatus, and acomputer-readable medium for rendering image data on a 3D display aredisclosed.

According to one aspect of the invention, a method is provided forrendering image data on a 3D display, said method comprising the stepsof:

-   -   receiving a first image signal;    -   rendering at least one colour component of the first image        signal in reduced spatial resolution to produce a second image        signal; and    -   spatial filtering said second image signal, wherein spatial        errors and view errors are balanced when reconstructing a full        resolution signal for the display.

According to yet another aspect of the invention, a signal processingsystem for rendering image data on a 3D display, comprising:

-   -   means for receiving a first image signal;    -   means for rendering at least one colour component of the first        image signal in reduced spatial resolution to produce a second        image signal; and    -   means for spatial filtering said second image signal, wherein        spatial errors and view errors are balanced when reconstructing        a full resolution signal for the display.

According to yet another aspect of the invention, a computer-readablemedium having embodied thereon a computer program for rendering imagedata for 3D display for processing by a computer, is provided, whereinthe computer program comprises:

-   -   a code segment for rendering at least one colour component of        the first image signal in reduced spatial resolution to produce        a second image signal; and    -   a code segment for spatial filtering said second image signal,        wherein spatial errors and view errors are balanced when        reconstructing a full resolution signal for the display.

The present invention has the advantage over the prior art that itreduces the computational load on a rendering system while maintainingthe perceived image quality of the image displayed on a 3D display.

These and other aspects, features and advantages of which the inventionis capable of will be apparent and elucidated from the followingdescription of embodiments of the present invention, reference beingmade to the accompanying drawings, in which

FIG. 1 illustrates a known signal processing system;

FIG. 2 illustrates view numbers on the respective sub-pixels for a9-view display according to the signal processing system illustrated inFIG. 1;

FIG. 3 illustrates a schematic perspective view of a multi-view displaydevice which may be used with the various embodiments of the invention;

FIG. 4 illustrates a signal processing system according to oneembodiment of the invention;

FIG. 5 illustrates a signal processing system according to anotherembodiment of the invention;

FIG. 6 illustrates view numbers on the respective sub-pixels for a9-view display according to the signal processing system illustrated inFIG. 5; and

FIG. 7 illustrates a computer readable medium according to oneembodiment of the invention.

The following description focuses on an embodiment of the presentinvention applicable to a video display systems and in particular to a3D video display system. However, it will be appreciated that theinvention is not limited to this application but may be applied to manyother video display systems. Furthermore, the invention applies torendering of 2.5D signals (regular video augmented with depth), stereosignals (a left-eye and right-eye regular video signal) or evenrendering of multi-view (e.g. 9 images for 9-view display). In addition,the invention applies to any type of image data such as, for example,video signals, still images, etc., although the calculation load savingsis more important for video since it requires real-time processing.

In the following example, a direct-view type of 3D-LCD lenticular arraydisplay device 100 having a slanted arrangement of lenticulars will beinitially described with reference to FIG. 3 in order to illustrate thepresent invention.

It will be understood that the Figures are merely schematic and are notdrawn to scale. For clarity of illustration, certain dimensions may havebeen exaggerated while other dimensions may have been reduced. Also,where appropriate, the same reference numerals and letters are usedthroughout the Figures to indicate the same parts and dimensions.

Referring to FIG. 3, the display device 10 includes a conventional LCmatrix display panel 11 used as a spatial light modulator and comprisinga planar array of individually addressable and similarly sizedlight-generating elements 12 arranged in aligned rows and columnsperpendicularly to one another. While only a few light-generatingelements are shown, there may, in practice, be around 800 columns (or2400 columns in colour, with RGB triplets used to provide a full colourdisplay) and 600 rows of display elements. Such panels are well knownand will not be described here in more detail.

The light-generating elements 12 are substantially rectangular in shapeand are regularly spaced from one another with the light-generatingelements in two adjacent columns being separated by a gap extending incolumn (vertical) direction and with the display elements in twoadjacent rows being separated by a gap extending in the row (horizontal)direction. The panel 11 is of the active matrix type in which eachlight-generating element is associated with a switching element,comprising for example, a TFT or thin film diode, TDF, situated adjacentthe light-generating element.

The display panel 11 is illuminated by a light source 14, which, in thisexample, comprises a planar backlight extending over the area of thedisplay element array. Light from the source 14 is directed through thepanel with the individual light-generating elements being driven, byappropriate application of drive voltages, to modulate this light inconventional manner to produce a display output. The array oflight-generating elements constituting the display produced thuscorresponds with the structure of light-generating elements, eachlight-generating elements, each light-generating element providing arespective display pixel. A computing means 18 computes luminance valuesfor the respective light-generating elements on basis of an inputsignal.

Over the output side of the panel 11, opposite that facing the lightsource 14, there is disposed a lenticular sheet 15 comprising an arrayof elongate, parallel, lenticules, or lens elements, acting as opticaldirector means to provide separate images to a viewer's eyes, producinga stereoscopic display to a viewer facing the side of the sheet 15remote from the panel 11. The lenticules of the sheet 15, which is ofconventional form, comprise optically (semi) cylindrically converginglenticules, for example, formed as convex cylindrical lenses or gradedreflective index cylindrical lenses. Autostereoscopic display deviceusing such lenticular sheets in conjunction with matrix display panelsare well known in the art although, unlike the conventional arrangementin such apparatus, with lenticules extending parallel to the displaypixel columns (corresponding to the display element columns), thelenticules in the apparatus of FIG. 3 are arranged slanted with respectto the columns of the light-generating elements, that is, their mainlongitudinal axis is at an angle to the column direction of thestructure of light-generating elements. This arrangement has been foundto provide a number of benefits in terms of reduced resolution loss andenhanced masking of the black area between light-generating elements, asis described in the patent application with number EP-A-0791 847. Thedescription of the operation of the display illustrated in FIG. 3 isdescribed in patent application PHNL050033EPP which is incorporatedherein by reference.

Briefly, the rendering process comprises several operations. First, animage is calculated for every view (e.g. from video+depth, or fromstereo). The image is then properly scaled to the view resolution. Theimage is then properly shifted to the subpixel positions of the view. Itwill be understood by those skilled in the art that some or all of theseoperations may be combined. For example, as illustrated in FIG. 2, thevertical scaling is done separately and then the view renderer performsall of the horizontal processing of the three operations.

In the Human Visual System (HVS), sharpness impression is mainlydetermined by luminance components, significantly less by chrominance.It is suggested that this also holds for depth perception. Furthermore,consider that most of the signal energy resides in the luminancecomponents. Further consider that colour space conversion is arelatively inexpensive operation when compared to rendering.

As the sharpness impression is mainly determined by luminancecomponents, and the luminance is most prominent part of the G signal,the most promising candidates for reduction of vertical resolution arethe B signal and in lesser extent the R signal. According to a firstembodiment of the invention, the B and R components are not calculatedfor every line in the frame. For example, the B and R components areonly calculate on every even line in the frame and a vertical averagebetween the even lines is used to calculate the B/R signals on the oddlines. As a result, the B and/or R components have a 50% reducedvertical resolution.

FIG. 4 illustrates a video signal processing system according to thefirst embodiment of the invention. It will be understood by thoseskilled in the art that the video processing system may be part of adisplay apparatus 200 e.g. a television, computer monitor, handhelddevice, etc. The rendering system 201 receives a YUVD signal, which isconverted into a RGBD signal in a known manner by a converter 202. TheRGBD is then scaled by a scaler 204 into the individual R, G, B, Dcomponents. In this embodiment, the RD, GD, and BD components for eacheven line in the frame are sent to at least one view renderer 206 toproduce new R, G, B signals for the even lines. The R, G, B, signals forthe even lines are then merged together in a merged unit 210. Inaddition, the GD component for each odd line in the frame is sent to aview renderer 208 (which behaves similar to 206) to produce a new Gsignal for each odd line in the frame. As will be described below inmore detail, the view renderers 206, 208 spatially filter theirrespective output signals in such a manner so as to minimize visibleartefacts caused by spatial and view errors produced during therendering process. As described above, an average value of the R and Bsignals for the even lines on each side of the odd lines are then mergedin the merge unit 212 with the calculated G signal to create an RGBsignal of the odd lines of the frame. The RGB signals for the even andodd lines are then combined in a unit 214 to create a final RGB signal,which is sent to a display 216.

As mentioned above, the rendering process produces spatial errors andview errors. The spatial error refers to the spatial distance. Thecloser the spatial distance, the more correlated the sample values, soclose spatial position provides minimal error. The view error refers tothe view number. Large differences in view numbers relate to largedisparities, hence a minimum view difference provides minimal error. Aview error of 0 only allows the use of sample values from the same view,resulting in very large spatial distances and thus leads to asignificant overall error. A minimal spatial error results in some casesin a very large view error resulting in very large disparities and thusleads to a significant overall error. In this embodiment of theinvention, the two errors are balanced using spatial filtering resultingin good image quality.

Experiments showed that this solution yields good results. Note alsothat the error is not just in vertical resolution, but also in depth. Avertical offset of one line results in a 1 view error. By choosingdifferent filter topologies, spatial accuracy may be traded for depthaccuracy. Thus, the spatial filter design takes both the spatialproperties and the depth properties of the display into account.According to one embodiment of the invention, a spatial filter isselected which tries to balance the correction of the spatial error withthe correction of the view error so that neither error produces manyvisible artefacts. This solution proved to introduce hardly any visibleartefacts. Since the computational load of the average operation can beneglected compared to view rendering, this reduces the computations by⅓.

It will be understood by those skilled in the art that the invention mayalso be used to calculate the R, G, B values for the odd lines and usethe R and B values of the odd lines to estimate the R and B values ofthe even lines. Furthermore, it will also be understood that thetraditional calculation of R and B values for odd lines can be skippedfor every other odd line, every 3^(rd) line, every 4^(th) line, etc.

According to another embodiment of the invention, the rendering isperformed in the YUV domain. FIG. 5 illustrates a video signalprocessing system according to this embodiment of the invention. It willbe understood by those skilled in the art that the video processingsystem may be part of a display apparatus 300 e.g. a television,computer monitor, handheld device, etc. The rendering system 301receives a YUVD signal, which is applied to a scaler 302. The YUVDsignal is scaled by the scaler 302 into individual Y, U, V, Dcomponents. In this embodiment, the YD, UD, VD components are sent to aview renderer 304 to produce new Y, U, V signals. The Y, U, V signalsare then merged back together in a merge unit. The merged YUV signal isthen converted into an RGB signal by a converter 308. The conversion ofthe YUV signal to the RGB signal takes both the spatial properties anddepth properties of the display into account by using a specificallychosen spatial filter as described above. The RGB signal is then sent toa display 310.

At first glance, this does not provide any cost saving while introducingan error. First, the error should be reduced as mush as possible. Laterit will be shown how a reduction of the resolution of the U/V signalsleads to significant cost savings. The view renderer is designed tooperate on the R, G and B sub-pixel locations of the screen. For optimalmapping of YUV on these RGB locations we take the colour spaceconversion matrix into account; as an example, the ITU-R BT.601-5 colourmatrix given byY′=0.299*R′+0.587*G′+0.114*B′U′=−0.169*R′−0.331*G′+0.500*B′V′=0.500*R′−0.419*G′−0.081* B′R′=Y′+1.402*V′G′=Y′−0.344*U′−0.714*V′B′=Y′+1.772*U′

It is optimal to use the most prominent colour component, hence: Y ismapped on G (i.e., it is processed as if it were a G signal); U ismapped on B, V is mapped on R. This mapping of the YUV on RGB sub-pixellocations as is shown in FIG. 6.

The conversion from YUV to RGB, yields a significant depth error unlessproper precautions are taken. The most dominant contribution shall betaken from the correct location. This results in the following pixelsused to calculate R, G and B:R←(Y[x+1], V[x])G←(Y[x], V[x−1], U[x+1])B←(Y[x−1], U[x])where x denotes the current pixel position.

This setup results in a maximum view error of 1. Note that taking thevalues from neighbouring pixels ([x−1] or [x+1]) is not the closestspatial position. If only the optimal spatial position was taken intoaccount, all values would have been taken from position [x].

Experiments have shown that this conversion results only in marginaldeterioration of the perceived image quality.

As a further refinement, some filtering may be applied either usinglinear or statistical order filters. Examples:

For R, liner filter with Y[y,x+1] and Y[y,x−2]

For R, median filter with Y[y,x+1] and Y[y−1,x+1] and Y[y,x−2]

For B, linear filter with Y[y,x−1] and Y[y,x+2]

For B, median filter with Y[y,x−1] and Y[y+1,x−1] and Y[y,x+2]

where y denotes current line position.

Now we have obtained renderer instantiations that process U/V signals.This allows taking advantage of the reduced signal energy and bandwidthand perception sensitivity on these channels by:

-   -   executing the vertical scalar in reduced horizontal resolution        (typically TV signals are 4:2:2 formatted, which reduces the        amount of U/V data in the vertical scalar by 50%);    -   reducing the complexity e.g. number of filter tabs and reduced        accuracy, of the vertical scalar;    -   reducing the complexity e.g. number of filter tabs and reduced        accuracy, of the horizontal scalar/resampler that is part of the        renderer.

Roughly, the complexity of U/V processing may be reduced at least by 50%compared to Y processing. We may neglect the fact that the YUV/RGBmatrix now runs on higher data rates. Then, this results in a reductionof ⅓.

According to another embodiment of the invention, the above mentionedreduced resolution of U/V signals is exploited. Note that the inputsignal is usually 4:2:2 formatted, only half of the pixels in thehorizontal direction should be processed during rendering. Forsimplicity of this explanation, we propose to execute the depth rendereron the reduced U/V resolution without any modification; simplycalculating only half of the output values. Then the YUV to RGBconversion needs to be adapted, at every odd pixel position where U/Vvalues are missing. The following data use is proposed for these oddpositions:R←(Y[y,x+1], V[y−2,x+1])G←(Y[y,x], V[y,x−1], U[y,x+1])B←(Y[y,x−1], U[y−2,x+1])

However, also the calculation at the even positions need to be adapted,since U/V values cannot be obtained from neighbouring pixel locations;this is a solution:R←(Y[x+1], V[x])G←(Y[x], V[x+2], U[x−2])B←(Y[x−1], U[x])

This results in a maximum view error of 1. Note also that data with avertical distance of two lines is used (not from the previous line).This allows straight forward combination of this embodiment with thefirst embodiment that reduced the vertical resolution by 2. Note alsothat the rather large spatial error of two lines is only in the U and Vsignals.

As a further refinement, some filtering may be applied, either usinglinear or statistical order filters. For example:

For R, linear filter with V[y−2,x+1] and V[y+2,x−1]

For B, linear filter with U[y-z,x+1] and U[y+2,x−1]

These pixel locations show spatial symmetry around the required pixellocation.

The cost saving is immediately clear: both the vertical scaling and viewrenderer require only 50% of the U/V calculations. Hence, it reduces thecalculations by ⅓.

An additional option in the invention is to apply depth depended signalprocessing. It is known from perception research the depth impression isrelated to brightness/contrast properties: far-away parts of a sceneappear more “misty” than close-by parts. This knowledge can easily beapplied in the invention at the rendering stage, since now luminance anddepth information are both available at the rendering stage and depthdependent brightness/contrast adaptation can easily be obtained, e.g. bymeans of a variable gain (depth controlled) or a lookup-table. Thisresults in an improved depth impression. Another example of depthdependent signal processing relates to sharpness. Often, objects in thebackground are out of focus. This observation can be applied in thesignal processing: blurring the background improves the depthimpression. Therefore depth dependent sharpness reduction may enhancethe depth impression. Since sharpness impression is mainly determined bythe luminance component of a video signal, it is advantageous to applythis depth dependent sharpness filter in the YUV domain. Furthermore,the current invention provides a particularly advantageous system sincethis depth dependent filtering can be seamlessly integrated in therendering unit that is processing the YD signals at relatively low extracost. The main function of the rendering is to provide a disparity depthcue to the observer. By means of dependent signal processing, additionaldepth cues are provided.

The various embodiments are designed for easy combination to obtainmaximum savings: without even taking the simplified filters of thesecond embodiment into account, the first and third result both in areduction of 50% in U/V processing, so 300% for regular RGB becomes 100%for Y and 25% for U and V respectively. This results in a totalreduction of 50%.

According to another embodiment of the invention, the invention can beused in a switchable 2D/3D display where the display can be put in amode where it operates as a regular 2D display or it can be switched toa 3D mode. As a result, the pixel selection for the YUV to RGBconversion depends on the selected 2D or 3D display mode.

In another embodiment of the invention according to FIG. 7, a computerreadable medium is illustrated schematically. A computer-readable medium700 has embodied thereon a computer program 710 for rendering video dataon a 3D display, for processing by a computer 713. The computer programcomprises a code segment 714 for rendering at least one colour componentof the first video signal in reduced spatial resolution to produce asecond signal; and a code segment 715 for spatial filtering said secondvideo signal wherein spatial errors and view errors are balanced whenreconstructing a full resolution signal for the display.

The invention can be implemented in any suitable form includinghardware, software, firmware or any combination of these. The elementsand components of an embodiment of the invention may be physically,functionally and logically implemented in any suitable way. Indeed, thefunctionality may be implemented in a single unit, in a plurality ofunits or as part of other functional units. As such, the invention maybe implemented in a single unit, or may be physically and functionallydistributed between different units and processors.

Although the present invention has been described above with referenceto a specific embodiments, it is not intended to be limited to thespecific form set forth herein. Rather, the invention is limited only bythe accompanying claims and, other embodiments than the specific aboveare equally possible within the scope of these appended claims, e.g.different signal processing systems than those described above.

In the claims, the term “comprises/comprising” does not exclude thepresence of other elements or steps. Furthermore, although individuallylisted, a plurality of means, elements or method steps may beimplemented by e.g. a single unit or processor.

Additionally, although individual features may be included in differentclaims, these may possibly advantageously be combined, and the inclusionin different claims does not imply that a combination of features is notfeasible and/or advantageous. In addition, singular references do notexclude a plurality. The terms “a”, “an”, “first”, “second” etc do notpreclude a plurality. Reference signs in the claims are provided merelyas a clarifying example and shall not be construed as limiting the scopeof the claims in any way.

1. A method for rendering image data on a 3D display, said methodcomprising: receiving, by a rendering system, a first image signal;rendering,by a converter, a scaler and a view renderer, at least onecolor component of the first image signal in reduced spatial resolutionto produce a second image signal; and spatial filtering, in the viewrenderer, said second image signal, such that spatial errors and viewerrors are balanced when reconstructing a full resolution signal for the3D display.
 2. The method according to claim 1, comprising selectinglower resolution color components based on sensitivity of the humanvisual system (HVS).
 3. The method according to claim 1, wherein saidspatial filtering uses a spatially closest available pixel value with amaximum view error.
 4. The method according to claim 1, wherein the 3Ddisplay is an RGB display and the color components with reduced spatialresolution are B and/or R components.
 5. The method according to claim1, wherein selection of a spatial filter for said spatial filteringtakes into account the spatial properties and view properties of the 3Ddisplay.
 6. The method according to claim 4, wherein the B and/or Rcomponents have 50% reduced vertical resolution.
 7. The method accordingto claim 6, wherein the spatial filter comprises a vertical averageoperation between neighboring lines.
 8. The method according to claim 1,wherein the rendering is performed in a color space different from adisplay color space of the 3D display.
 9. The method according to claim8, comprising applying depth dependent filtering when rendering at leastone of the color components to provide additional depth cues.
 10. Themethod according to claim 8, wherein the mapping of the components fromthe rendering colour space to the display color space depends on themost prominent contribution from the rendering components to the displaycomponents.
 11. The method according to claim 10, wherein processing isperformed in a YUV domain for an RGB display and the mapping is Y on G,U on B, and V on R.
 12. The method according to claim 8, wherein theconversion of the rendering color space to the display color space takesboth the spatial properties and depth properties of the display intoaccount.
 13. The method according to claim 8, wherein processing isperformed in a YUV domain and the spatial resolution on the U and Vsignals having 50% reduced horizontal resolution.
 14. The methodaccording to claim 13, wherein resolution of the U and V signal havingreduced vertical resolution.
 15. The method according to claim 13,comprising performing the rendering on U and V with less accuracy thanthe rendering on Y.
 16. The method according to claim 11, wherein pixelselection for the YUV to RGB conversion depends on selected displaymode.
 17. A signal processing system for rendering image data on a 3Ddisplay, comprising: means for receiving a first image signal; means forrendering at least one color component of the first image signal inreduced spatial resolution to produce a second image signal; and meansfor spatial filtering of said second image signal, wherein spatialerrors and view errors are balanced when reconstructing a fullresolution signal for the 3D display.
 18. A display apparatus forrendering image data for a 3D display, comprising: means for receiving afirst image signal; means for rendering at least one color component ofthe first image signal in reduced spatial resolution to produce a secondimage signal; and means for spatial filtering of said second imagesignal, wherein spatial errors and view errors are balanced whenreconstructing a full resolution signal for the 3D display.
 19. Anon-transitory computer-readable medium having embodied thereon acomputer program for rendering image data for 3D display for processingby a computer, the computer program comprising: a code segment forrendering at least one color component of the first image signal inreduced spatial resolution to produce a second image signal; and a codesegment for spatial filtering of said second image signal, whereinspatial errors and view errors are balanced when reconstructing a fullresolution signal for the display.